Long-term meteorological and greenhouse gas measurements are used to assess the performance of global climate models in simulating past weather conditions. However, routine in situ observations of aerosol properties remain limited. Field campaigns address this issue by obtaining detailed measurements of aerosol mass, composition, size distribution, and optical properties as well as measurements of trace gas precursors and meteorology that control the life-cycle of aerosols. This information is collected both at the surface and aloft over local and regional spatial scales, and often coincides with satellite overpasses so that remote sensing and in-situ data can be compared. In contrast with most modeling studies that focus on a subset of data, the Aerosol Modeling Testbed is designed to fully utilize the wide range of measurements to address uncertainties in the predictions of aerosol radiative forcing.
MILAGRO is the first case developed for the Aerosol Modeling Testbed. Field campaigns tend to focus on specific atmospheric processes and the relatively short sampling periods (typically a few weeks) limit the conclusions drawn by model evaluation studies. Therefore, several representative future testbed cases will be developed for the Aerosol Modeling Testbed so that the performance of new and updated aerosol process modules can be evaluated over a wide range of meteorological conditions.